Return Pump/heater recommendations

700 is what you will end up with with a 1262 or OR3500 after headloss. You can add a gate valve on the overflow for maintenance but its really not needed and should never ever be throttled or restricted or a flood is in your future. You add a gate valve on the discharge side of the pump and throttle at that point if cutting back is needed, it even makes the pump more efficient and draw lower wattage in most cases as centrifugal pumps only draw the power required to do the work at hand plus a little fo inefficiencies.